Transmission device

ABSTRACT

A fastening portion is formed from a rivet hole of a first side wall portion of a clutch drum, a rivet hole of a second side wall portion of a clutch drum, and a rivet that is inserted into the rivet hole and the rivet hole to hold together the first side wall portion and the second side wall portion. The fastening portion is provided between a first engagement side oil chamber enclosed by the clutch drum and a clutch piston, and a second engagement side oil chamber enclosed by the clutch drum and a clutch piston.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application Nos. 2011-075570 and2011-241425 filed on Mar. 30, 2011 and Nov. 2, 2011, respectively,including the specifications, drawings and abstracts are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a transmission device that includes afirst clutch, and a second clutch disposed circumferentially inward ofthe first clutch.

Description of the Related Art

A proposed example of this type of transmission device in the pastincludes a first clutch and a second clutch. The first clutch includes afirst clutch drum that holds a plurality of clutch plates; a firstclutch piston that is in spline engagement with an inner circumferentialsurface of the first clutch drum, and moves in the axial direction topress the clutch plates; and a first cancel plate that defines togetherwith the first clutch piston a cancel oil chamber for cancelingcentrifugal hydraulic pressure. The second clutch includes a secondclutch drum that holds a plurality of clutch plates; a second clutchpiston that is in spline engagement with an inner circumferentialsurface of the second clutch drum, and moves in the axial direction topress the clutch plates; and a second cancel plate that together withthe second clutch piston defines a cancel oil chamber for cancelingcentrifugal hydraulic pressure, wherein the second clutch is disposedcircumferentially inward of the first clutch so as to overlap with thefirst clutch as viewed from the radial direction (e.g., see JapanesePatent Application Publication No. 2010-48381 (JP 2010-48381 A)). Thesecond clutch drum of the transmission device is formed from a cylinderportion that holds the clutch plates and axially supports the firstcancel plate, and a drum portion that radially supports the cylinderportion, wherein the cylinder portion is secured to the drum portion bya snap ring.

SUMMARY OF THE INVENTION

However, if the cylinder portion of the second clutch drum is fixed by asnap ring to the drum portion as in the transmission device describedabove, the axial length of the drum portion must be increased in orderto form a snap ring groove in the drum portion and ensure the strengthof the drum portion in the area of the snap ring groove. This mayincrease the overall axial length of the second clutch, and interferewith efforts to achieve a more compact device.

A transmission device of the present invention achieves a more compacttransmission device that includes a first clutch, and a second clutchdisposed circumferentially inward of the first clutch.

The transmission device of the present invention employs the followingto achieve the above.

A transmission device according to the present invention includes afirst clutch that includes a first clutch drum and a first piston; and asecond clutch that includes a second clutch drum and a second piston,and is disposed circumferentially inward of the first clutch. In thetransmission device, the first clutch includes a first clutch oilchamber enclosed by the first clutch drum and the first piston, thesecond clutch includes a second clutch oil chamber enclosed by the firstclutch drum and the second piston. In addition, a fastening portion,formed from a first through hole of a first side wall portion of thefirst clutch drum, a second through hole of a second side wall portionof the second clutch drum, and a rivet that is inserted into the firstand second through holes and holds together the first and second sidewall portions, is provided between the first clutch oil chamber and thesecond clutch oil chamber.

In the transmission device of the present invention, the fasteningportion is formed from the first through hole of the first side wallportion of the first clutch drum, the second through hole of the secondside wall portion of the second clutch drum, and the rivet that isinserted into the first and second through holes and holds together thefirst and second side wall portions. The fastening portion is providedbetween the first clutch oil chamber enclosed by the first clutch drumand the first piston, and the second clutch oil chamber enclosed by thefirst clutch drum and the second piston. By thus using the rivet to holdtogether the first side wall portion of the first clutch drum and thesecond side wall portion of the second clutch drum to fix the firstclutch drum and the second clutch drum, there is no need to provide asnap ring and a section on a support member of the second clutch drumrequired for holding the snap ring, and the fastening portion can beprovided between the first clutch oil chamber and the second clutch oilchamber. Therefore, an increase in the axial length can be suppressed toachieve a more compact device. In addition, torque is transmittedbetween the first and second clutch drums through the rivet. There isthus no need to form a spline for transmitting torque between the firstand second clutch drums, and processing costs can be reduced as aconsequence.

The first through hole of the first clutch drum may be formed with aninner diameter that becomes smaller from an outer side toward a second,clutch drum side of the first clutch drum. If the rivet is thus caulkedfrom the outer side of the first clutch drum, the rivet can sufficientlyfill the rivet hole and the rivet can be more strongly fixed to thefirst clutch drum.

The fastening portion that fastens the first clutch drum and the secondclutch drum may be disposed circumferentially inward of the first clutchoil chamber and circumferentially outward of the second clutch oilchamber.

The first clutch may further include a first cancel plate, and thesecond clutch may further include a second cancel plate. In addition, atleast a portion of the second clutch may overlap with the first clutchas viewed from a radial direction, and at least a portion of thefastening portion may be included within a range of a width, in an axialdirection of the transmission device, of a space enclosed by the firstclutch drum and the first cancel plate and a space enclosed by the firstclutch drum and the second cancel plate. Thus, an increase in the axiallength can be suppressed to achieve a more compact transmission device.

The second side wall portion of the second clutch drum may contact thefirst cancel plate, and the first cancel plate and the second side wallportion of the second clutch drum may be fastened to the first clutchdrum. Thus, when the first cancel plate presses the second clutch drumdue to centrifugal hydraulic pressure generated in the first clutch oilchamber of the first clutch, the fulcrum point (portion where the firstclutch drum and the second clutch drum are fastened) and the force point(section where the second clutch drum supports the first cancel plate)of a torsional moment that acts on the second clutch drum correspond tosubstantially the same position. Therefore, a large torsional momentacting on the second clutch drum can be well suppressed.

A ring-shaped fixing portion may axially extend from the first side wallportion of the first clutch drum. In addition, an aligning portion maybe formed axially extending from the fixing portion, and the firstcancel plate and the second clutch drum may be fitted to the aligningportion of the fixing portion and fastened to the fixing portion. Thus,the first clutch drum, the first cancel plate, and the second clutchdrum can be easily fastened together. In addition, by fitting the firstcancel plate and the second clutch drum to the aligning portion axiallyextending from the fixing portion, the first cancel plate and the secondclutch drum can be easily aligned.

The first piston of the first clutch may be axially movable by hydraulicpressure supplied to the first clutch oil chamber on an innercircumferential side of the first clutch drum, and define together withthe first cancel plate a first cancel oil chamber that cancelscentrifugal hydraulic pressure. The second piston of the second clutchmay be axially movable by hydraulic pressure supplied to the secondclutch oil chamber on an inner circumferential side of the second clutchdrum, and define together with the second cancel plate a second canceloil chamber that cancels centrifugal hydraulic pressure. The firstclutch drum may include an inner cylinder portion that axially extendsfrom an inner circumferential portion of the first side wall portion.The first piston may be supported axially slidable by the fixing portionof the first clutch drum, and define the first clutch oil chambertogether with the first side wall portion and the fixing portion of thefirst clutch drum. The second clutch drum may axially support the firstcancel plate. The second piston may be supported axially slidable by theinner cylinder portion of the first clutch drum and formed so as toslidingly contact an inner circumferential surface of the fixing portionof the first clutch drum, and define the second clutch oil chambertogether with the inner cylinder portion, the first side wall portion,and the fixing portion of the first clutch drum. By thus utilizing thefixing portion extending from the first side wall portion of the firstclutch drum, the first and second clutches can be easily configured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view that shows an essential portion of anautomatic transmission 20 according to an embodiment of the presentinvention;

FIG. 2 is a frontal view of a clutch drum 30 as seen from the right sidein FIG. 1;

FIG. 3 is an enlarged sectional view that shows a fixing portion 304 ofthe clutch drum 30 and a surrounding area;

FIG. 4 is an enlarged sectional view that shows a second oil passage 302c formed in a first side wall portion 302 of the clutch drum 30 and asurrounding area;

FIG. 5 is an enlarged sectional view that shows a portion of contactbetween a sleeve 52 and a stepped portion 303 d of an inner cylinderportion 303 of the clutch drum 30;

FIG. 6 is an enlarged view of an essential portion that shows an endportion of the sleeve 52; and

FIG. 7 is an enlarged sectional view that shows the fixing portion 304of the clutch drum 30 and the surrounding area.

DETAILED DESCRIPTION OF THE EMBODIMENT

Next, an embodiment of the present invention will be described.

FIG. 1 is an enlarged sectional view that shows an essential portion ofan automatic transmission 20 according to an embodiment of the presentinvention. The automatic transmission 20 according to the embodiment isconfigured as a stepped transmission and mounted in a vehicle. As shownin FIG. 1, the automatic transmission 20 includes an input shaft 21, aswell as the clutches C1 and C2, a plurality of other clutches and brakes(not shown), and a planetary gear mechanism 50 for changing a powertransmission path from the input shaft 21 to an output shaft (notshown). The clutches C1 and C2, the plurality of other clutches andbrakes, and the planetary gear mechanism 50 are accommodated inside atransmission case (not shown). Note that the input shaft 21 of theautomatic transmission 20 is connected to a crankshaft of an enginethrough a torque converter or the like, and the output shaft isconnected to a drive wheel through a differential mechanism(differential gear) or the like (none of which are shown in thedrawings).

The clutch C1 is configured as a multi-plate friction hydraulic clutch.The clutch C1 includes a clutch drum 30 that is supported rotatablearound the input shaft 21 through a bearing 51; a clutch hub 31 that isfixed to a ring gear, for example, of the planetary gear mechanism 50; aplurality of ring-shaped clutch plates (mating plates) 32 that isslidably supported on an inner circumferential surface of the clutchdrum 30 through a spline; a plurality of ring-shaped clutch plates(friction plates) 33 that is slidably supported on an outercircumferential surface of the clutch hub 31 through a spline; a clutchpiston 35 that is fitted axially slidable on the inner circumferentialsurface of the clutch drum 30 and movable toward the clutch plates 32,33, and defines together with the clutch drum 30 a first engagement sideoil chamber (first clutch oil chamber) 34; a cancel plate 36 thatdefines together with the clutch piston 35 a first cancel oil chamber 37for canceling centrifugal hydraulic pressure generated inside the firstengagement side oil chamber 34; and a return spring 38 that is disposedbetween the clutch piston 35 and the cancel plate 36. The clutch drum 30is configured from a first outer cylinder portion 301 that supports theclutch plates 32, a first side wall portion 302 that extends radiallyinward from an end of the first outer cylinder portion 301, and an innercylinder portion 303 that axially extends from an inner circumferentialportion of the first side wall portion 302. The inner cylinder portion303 of the clutch drum 30 is press-fit (fitted) with a sleeve 52 so asto enable the sleeve 52 to rotate together with the inner cylinderportion 303. The sleeve 52 is rotatably supported by a fixed member(fixed shaft) 600 that is integrated with the transmission case, forexample, and rotatably supports the input shaft 21. Thus, the clutchdrum 30 is rotatable around the axis of the input shaft 21. One endsurface (on the left side of the figure) of the sleeve 52 contacts aninner surface of a stepped portion 303 d formed on the inner cylinderportion 303, whereby the sleeve 52 is positioned in the axial direction.

The clutch C2 is configured as a multi-plate friction hydraulic clutch,and disposed inward of the clutch C1 so as to overlap with the clutch C1as viewed from the radial direction. The clutch C2 includes a clutchdrum 40 that contacts (axially supports) a radially-extending innercircumferential portion of the cancel plate 36 biased by the returnspring 38 toward the left side of the figure, and fastened to the clutchdrum 30 together with the cancel plate 36; a clutch hub 41 that is fixedto a carrier, for example, of the planetary gear mechanism 50; aplurality of ring-shaped clutch plates (mating plates) 42 that isslidably supported on an inner circumferential surface of the clutchdrum 40 through a spline; a plurality of ring-shaped clutch plates(friction plates) 43 that is slidably supported on an outercircumferential surface of the clutch hub 41 through a spline; a clutchpiston 45 that is fitted axially slidable on the inner circumferentialsurface of the clutch drum 40 and movable toward the clutch plates 42,43, and defines together with the clutch drum 30 a second engagementside oil chamber (second clutch oil chamber) 44; a cancel plate 46 thatdefines together with the clutch piston 45 a second cancel oil chamber47 for canceling centrifugal hydraulic pressure generated inside thesecond engagement side oil chamber 44; and a return spring 48 that isdisposed between the clutch piston 45 and the cancel plate 46. Theclutch drum 40 is configured from a second outer cylinder portion 401that supports the clutch plates 42, and a second side wall portion 402that extends radially inward from an end of the second outer cylinderportion 401. Note that the cancel plate 36 of the clutch C1 may besupported in the axial direction by a member other than the clutch drum40 of the clutch C2.

A ring-shaped fixing portion 304 extends axially inward from asubstantially radial center portion of the first side wall portion 302of the clutch drum 30 of the clutch C1. A ring-shaped aligning portion305 also extends axially inward from an end portion on the innercircumferential side of the fixing portion 304. The cancel plate 36 ofthe clutch C1 includes an outer circumferential portion 361 thatslidingly contacts an inner circumferential portion of the clutch piston35 through a seal member; a coupling portion 362 that axially extendsfrom the outer circumferential portion 361; and an inner circumferentialportion 363 that extends radially inward from the coupling portion 362.One end surface of the inner circumferential portion 363 contacts anaxially inward end surface of the fixing portion 304 of the clutch drum30 and the other end surface of the inner circumferential portion 363contacts the second side wall portion 402 of the clutch drum 40 of theclutch C2. In this state, the cancel plate 36 is fitted to an outercircumferential surface of the aligning portion 305, which extends fromthe fixing portion 304, together with the second side wall portion 402of the clutch drum 40.

FIG. 2 is a frontal view of the clutch drum 30 as seen from the rightside in FIG. 1. FIG. 3 is an enlarged sectional view that shows anessential portion of the fixing portion 304. As shown in the figures,the fixing portion 304 of the clutch drum 30 is formed with a pluralityof rivet holes 306 that extends axially inward from an end surface ofthe first side wall portion 302 of the clutch drum 30. Each of theplurality of rivet holes 306 is formed of a first hole portion 306 athat extends axially inward from the end surface of the first side wallportion 302, a second hole portion 306 b that extends axially inwardfrom the first hole portion 306 a such that an inner diameter of thesecond hole portion 306 b gradually decreases, and a third hole portion306 c that extends further axially inward from the second hole portion306 b such that an inner diameter of the third hole portion 306 cgradually decreases. The cancel plate 36 of the clutch C1 is also formedwith a plurality of rivet holes 363 a, each of which is in communicationwith the third hole portion 306 c of the rivet hole 306 of the fixingportion 304 when the inner circumferential portion 363 of the cancelplate 36 is fitted to the aligning portion 305. In addition, the secondside wall portion 402 of the clutch drum 40 of the clutch C2 is formedwith a plurality of rivet holes 402 a, each of which is in communicationwith the rivet hole 363 a of the cancel plate 36 when the innercircumferential portion of the second side wall portion 402 is fitted tothe aligning portion 305. A rivet 53 is inserted in the rivet holes 306,363 a, and 402 a. The rivet 53 is caulked from axially outward of theclutch drum 30 to fasten together the cancel plate 36 and the secondside wall portion 402 of the clutch drum 40 to the fixing portion 304 ofthe clutch drum 30.

Thus, the clutch drum 30, the cancel plate 36, and the clutch drum 40can be easily fastened together on the inner circumferential sides ofthe first engagement side oil chamber 34 and the first cancel oilchamber 37, and on the outer circumferential sides of the secondengagement side oil chamber 44 and the second cancel oil chamber 47. inaddition, the cancel plate 36 is axially supported by the second sidewall portion 402 of the clutch drum 40 that contacts the innercircumferential portion 363. As shown in FIG. 1, the portion where theclutch drum 30, the cancel plate 36, and the clutch drum 40 are fastened(in the embodiment, a range from one end to the other end of the rivet53) is included within a range of an axial width DO of the firstengagement side oil chamber 34 and the first cancel oil chamber 37 thatare spaces (oil chambers) enclosed by the clutch drum 30 and the cancelplate 36, and the second engagement side oil chamber 44 and the secondcancel oil chamber 47 that are spaces (oil chambers) enclosed by theclutch drum 30 and the cancel plate 46. Specifically, in the presentembodiment, the portion where the clutch drum 30, the cancel plate 36,and the clutch drum 40 are fastened is included within a range of anaxial width D1 of the first engagement side oil chamber 34 and the firstcancel oil chamber 37 that are the oil chambers of the clutch C1, andincluded within a range of an axial width D2 of the second engagementside oil chamber 44 and the second cancel oil chamber 47 that are theoil chambers of the clutch C2. More specifically, the portion where theclutch drum 30, the cancel plate 36, and the clutch drum 40 are fastenedis included within a range of a width D3 of a section where the firstengagement side oil chamber 34 and the first cancel oil chamber 37, andthe second engagement side oil chamber 44 and the second cancel oilchamber 47 overlap as viewed from the radial direction.

The clutch piston 35 of the clutch C1 is supported axially slidable bythe fixing portion 304 of the clutch drum 30 through a seal member, andslidingly contacts an inner circumferential surface of the first outercylindrical portion 301 of the clutch drum 30 through a seal member. Theclutch piston 35 thus defines, together with the first outer cylinderportion 301, the first side wall portion 302, and the fixing portion 304of the clutch drum 30, the first engagement side oil chamber 34. Theclutch piston 45 of the clutch C2 is supported axially slidable by theinner cylinder portion 303 of the clutch drum 30 through a seal member,and slidingly contacts an inner circumferential surface of the fixingportion 304 of the clutch drum 30 through a seal member. The clutchpiston 45 thus defines, together with the inner cylinder portion 303,the first side wall portion 302, and the fixing portion 304 of theclutch drum 30, the second engagement side oil chamber 44. By utilizingthe fixing portion 304 formed on the first side wall portion 302 of theclutch drum 30 in this manner, the first and second clutches can beeasily configured.

The fixed member 600 is formed with supply passages 31 a, 31 b that areconnected to a hydraulic control device (not shown) through an oilpassage (not shown) formed in the input shaft 21. The fixed member 600is also formed with a supply passage 31 c to which drained hydraulic oilis supplied from a hydraulic circuit of a lubrication system (not shown)that supplies lubricating oil to a lubrication target such as theplanetary gear mechanism 50 mounted in the automatic transmission 20. Inaddition, the sleeve 52 press-fit to the clutch drum 30 of the clutch C1is formed with an oil hole 52 a that is in communication with the supplypassage 31 a formed in the fixed member 600, and an oil hole 52 b thatis in communication with the supply passage 31 b. The inner cylinderportion 303 of the clutch drum 30 is formed with a relay oil passage 303a that is in communication with the oil hole 52 a of the sleeve 52, anda relay oil passage 303 b that is in communication with the oil hole 52b. The relay oil passage 303 b is in communication with the secondengagement side oil chamber 44. As shown in FIGS. 1 and 2, the firstside wall portion 302 of the clutch drum 30 is formed with a plurality(four in the embodiment) of first oil passages 302 a that radiallyextend in a radiating mariner. Each of the plurality of first oilpassages 302 a on the inner circumferential side thereof is incommunication with the relay oil passage 303 a formed in the innercylinder portion 303, and also in communication with the firstengagement side oil chamber 34 through an oil passage 302 b that is morecircumferentially outward than the fixing portion 304 and axiallyextends through an inner portion of the first side wall portion 302.Thus, the hydraulic control device and the first engagement side oilchamber 34 are connected through the supply passage 31 a of the fixedmember 600, the relay oil passage 303 a of the inner cylinder portion303 of the clutch drum 30, and the first oil passage 302 a and the oilpassage 302 b of the first side wall portion 302. Also, the hydrauliccontrol device and the second engagement side oil chamber 44 areconnected through the supply passage 3 lb of the fixed member 600, andthe relay oil passage 303 b of the inner cylinder portion 303 of clutchdrum 30.

In addition, the sleeve 52 press-fit to the clutch drum 30 of the clutchC1 is formed with an oil hole 52 c that is in communication with asupply passage 31 c formed in the fixed member 600. The inner cylinderportion 303 of the clutch drum 30 is formed with a relay oil passage 303c that is in communication with the oil hole 52 c of the sleeve 52. Therelay oil passage 303 c is formed so as to axially extend on an innercircumferential surface of the inner cylinder portion 303 of the clutchdrum 30, and an end (an end portion on the left side of FIG. 1) of therelay oil passage 303 c radially extends and is in communication withthe second cancel oil chamber 47 of the clutch C2. As shown in FIGS. 1and 2, the first side wall portion 302 of the clutch drum 30 is formedwith a plurality (four in the embodiment) of second oil passages 302 cthat radially extend in a radiating manner that alternates with theplurality of first oil passages 302 a so as not to overlap with theplurality of first oil passages 302 a as viewed from the axialdirection. Each of the plurality of second oil passages 302 c on theinner circumferential side thereof is in communication with the relayoil passage 303 c formed in the inner cylinder portion 303, and also incommunication with the first cancel oil chamber 37 through an oilpassage 302 d that axially extends through an inner portion of thefixing portion 304. Thus, a draining oil passage of the hydrauliccircuit of the lubrication system and the first cancel oil chamber 37communicate through the supply passage 31 c of the fixed member 600, therelay oil passage 303 c of the inner cylinder portion 303 of the clutchdrum 30, the second oil passage 302 c of the first side wall portion302, and the oil passage 302 d. Also, the draining oil passage of thehydraulic circuit of the lubrication system and the second cancel oilchamber 47 communicate through the supply passage 31 c of the fixedmember 600, and the relay oil passage 303 c of the inner cylinderportion 303 of clutch drum 30. By forming the first oil passages 302 aand the second oil passages 302 c on substantially the same plane insidethe first side wall portion 302 in this manner, an increase in the axiallength of the clutches C1, C2 can be suppressed. In addition, byalternately forming the first oil passages 302 a and the second oilpassages 302 c as viewed from the axial direction, hydraulic oil can beequally supplied to the first engagement side oil chamber 34 and thefirst cancel oil chamber 37 found into ring shapes. Here, as shown by anarrow in FIG. 4, the first and second oil passages 302 a, 302 cdescribed above can be easily formed by forming a hole portionpenetrating radially inward from an outer periphery of the first sidewall portion 302 of the clutch drum 30, and then press-fitting a plug(lid element) 54 to an opening portion of the hole portion positioned onthe outer circumferential side of the first side wall portion 302 asshown by a white arrow in FIG. 4 to close the opening portion.

FIG. 5 is an enlarged sectional view that shows a portion of contactbetween the sleeve 52 and the stepped portion 303 d of the innercylinder portion 303 of the clutch drum 30. FIG. 6 is an enlarged viewof an essential portion that shows an end portion of the sleeve 52. Asshown in the figures, at the end portion of the sleeve 52, a firstpassage 521 is formed at a plurality of locations (eight locations inthe embodiment) on an outer periphery of the sleeve 52. Each firstpassage 521 is in communication with the relay oil passage 303 c formedin the inner circumferential surface of the inner cylinder portion 303of the clutch drum 30, and axially extends toward an end surface 520that contacts the stepped portion 303 d of the inner cylinder portion303. In addition, at the end portion of the sleeve 52, a second passage522 is formed at a plurality of locations (eight locations in theembodiment). Each second passage 522 is formed more axially recessedthan the end surface 520 that contacts the stepped portion 303 d of theinner cylinder portion 303, and radially extending to providecommunication between the first passage 521 and an inner portion of thesleeve 52. The second passage 522 is formed so as to open widest at aposition that is in communication with the first passage 521, andgradually narrow in the axial direction in the vicinity of a radialcenter portion of the sleeve 52 from the position at which the secondpassage 522 is in communication with the first passage 521, after whichthe second passage 522 has the same cross-sectional shape up to theinner circumferential surface of the sleeve 52. The stepped portion 303d of the inner cylinder portion 303 is formed with an oil passage 303 eas shown in the figure.

Next, the operation to supply hydraulic oil to the oil chambers of theclutches C1, C2 of the automatic transmission 20 thus configured will bedescribed. When engaging the clutch C1 of the embodiment, hydraulic oilfrom the hydraulic control device is supplied to the first engagementside oil chamber 34 through the supply passage 31 a of the fixed member600, the relay oil passage 303 a of the inner cylinder portion 303 ofthe clutch drum 30, and the first oil passage 302 a and the oil passage302 b of the first side wall portion 302. Thus, hydraulic pressureacting on the first engagement side oil chamber 34 causes the clutchpiston 35 to move toward the clutch plates 32, 33 such that the clutchplates 32, 33 are sandwiched between the clutch piston 35 and a contactmember fixed to the clutch drum 30, thus coupling the clutch drum 30 andthe clutch hub 31 by the friction force acting between the clutch plates32, 33. When disengaging the clutch C1, the hydraulic control device(not shown) stops the supply of hydraulic pressure to the firstengagement side oil chamber 34, and the clutch piston 35 is biased bythe return spring 38 to move toward the reverse side of the clutchplates 32, 33, thus disengaging the coupling of the clutch drum 30 andthe clutch hub 31. When engaging the clutch C2, hydraulic oil from thehydraulic control device is supplied to the second engagement side oilchamber 44 through the supply passage 31 b of the fixed member 600, andthe relay oil passage 303 b of the inner cylinder portion 303 of theclutch drum 30. Thus, hydraulic pressure acting on the second engagementside oil chamber 44 causes the clutch piston 45 to move toward theclutch plates 43, 44 such that the clutch plates 43, 44 are sandwichedbetween the clutch piston 45 and a contact member fixed to the clutchdrum 40, thus coupling the clutch drum 40 and the clutch hub 41 by thefriction force acting between the clutch plates 43, 44. When disengagingthe clutch C2, the hydraulic control device (not shown) stops the supplyof hydraulic pressure to the second engagement side oil chamber 44, andthe clutch piston 45 is biased by the return spring 48 to move towardthe reverse side of the clutch plates 43, 44, thus disengaging thecoupling of the clutch drum 40 and the clutch hub 41.

If the automatic transmission 20 is operated with the first and secondengagement side oil chambers 34, 44 filled with hydraulic oil asdescribed above, centrifugal hydraulic pressure is generated in thefirst and second engagement side oil chambers 34, 44. Therefore, even ifthe supply of hydraulic pressure to the first and second engagement sideoil chambers 34, 44 is stopped in order to disengage the clutches C1 andC2, the clutch pistons 35, 45 may remain pressed axially inward (towardthe left side in FIG. 1) by the centrifugal hydraulic pressure, thusdelaying disengagement of the clutches C1, C2. Therefore, when theautomatic transmission 20 operates with the first and second engagementside oil chambers 34, 44 filled with hydraulic oil, the drainedhydraulic oil from the hydraulic circuit of the lubrication system issupplied to the first cancel oil chamber 37 of the clutch C1 through thesupply passage 31 c of the fixed member 600, the relay oil passage 303 cof the inner cylinder portion 303 of the clutch drum 30, and the secondoil passage 302 c of the first side wall portion 302, and the oilpassage 302 d. Also, the drained hydraulic oil from the hydrauliccircuit of the lubrication system is supplied to the second cancel oilchamber 47 of the clutch C2 through the supply passage 31 c of the fixedmember 600, and the relay oil passage 303 c of the inner cylinderportion 303 of clutch drum 30. As a consequence, centrifugal hydraulicpressure is also generated in the first and second cancel oil chambers37, 47, and the centrifugal hydraulic pressure presses the clutchpistons 35, 45 axially outward (toward the right side in FIG. 1) so thata force caused by the centrifugal hydraulic pressure generated in thefirst and second engagement side oil chambers 34, 44 and acting on theclutch pistons 35, 45 can be canceled out.

In this case, immediately after the vehicle starts operating, the firstand second cancel oil chambers 37, 47 are not fully filled withhydraulic oil and there is still air inside the first and second canceloil chambers 37, 47. The air still inside the first cancel oil chamber37 is discharged to outside the clutch C1 through the oil passage 302 d,the second oil passage 302 c of the first side wall portion 302, therelay oil passage 303 c of the inner cylinder portion 303 of the clutchdrum 30, and the first and second passages 521, 522 formed in the sleeve52 when hydraulic oil is supplied to inside the first cancel oil chamber37. The air still inside the second cancel oil chamber 47 is dischargedto outside the clutch C2 through the oil passage 302 d, the second oilpassage 302 c of the first side wall portion 302, the relay oil passage303 c of the inner cylinder portion 303 of the clutch drum 30, and thefirst and second passages 521, 522 formed in the sleeve 52. At suchtime, hydraulic oil having a high specific gravity moves by centrifugalforce circumferentially outward inside the first and second cancel oilchambers 37, 47, which causes air inside the first and second cancel oilchambers 37, 47 to move circumferentially inward. Therefore, by usingthe second passage 522 that extends radially inward along the endsurface 520 of the sleeve 52 as part of a path for discharging air, theair inside the first and second cancel oil chambers 37, 47 can bequickly discharged to outside while also suppressing an outflow ofhydraulic oil through the second passage 522. In addition, the secondpassage 522 that provides communication between the first passage 521and the inner portion of the sleeve 52 extends from the outercircumferential surface to the inner circumferential surface of thesleeve 52. Therefore, the zero-origin of the centrifugal hydraulicpressure in the first and second cancel oil chambers 37, 47 cancorrespond to the inner circumferential surface of the sleeve 52. As aconsequence, it is possible to suppress the outflow of hydraulic oilwhile promoting the discharge of air when filling the first and secondcancel oil chambers 37, 47 with hydraulic oil, and more suitably securecentrifugal hydraulic pressure in the first and second cancel oilchambers 37, 47. Note that the air discharged to outside the clutchesC1, C2 through the first and second passages 521, 522 of the sleeve 52is discharged through an inner portion of the transmission case tooutside the vehicle. Once the hydraulic oil inside the first and secondcancel oil chambers 37, 47 is discharged through the first and secondpassages 521, 522 of the sleeve 52, the hydraulic oil flows back to anoil pan (not shown) after being supplied to the lubrication target,i.e., the planetary gear mechanism 50, through the oil passage 303 eformed in the stepped portion 303 d of the inner cylinder portion 303 ofthe clutch drum 30, and a gap of the bearing 51.

Thus, when the automatic transmission 20 is operated with the firstcancel oil chamber 37 filled with hydraulic oil and centrifugalhydraulic pressure is generated in the first cancel oil chamber 37, thecentrifugal hydraulic pressure causes the inner circumferential portion363 of the cancel plate 36 to press the second side wall portion 402 ofthe clutch drum 40 of the clutch C2 in the axial direction. Here, asdescribed above, the inner circumferential portion 363 of the cancelplate 36 and the second side wall portion 402 of the clutch drum 40 arefastened by the fixing portion 304 of the clutch drum 30. Therefore,when the cancel plate 36 presses the clutch drum 40, the fulcrum point(portion where the clutch drum 40 and the clutch drum 30 are fastened)and the force point (section where the clutch drum 40 supports thecancel plate 36, i.e., portion of contact between the innercircumferential portion 363 of the cancel plate 36 and the second sidewall portion 402 of the clutch drum 40) of a torsional moment that actson the clutch drum 40 correspond to substantially the same position.Thus, a large torsional moment acting on the clutch drum 40 can besuppressed, and deformation of the clutch drum 40 can be wellsuppressed.

In the automatic transmission 20 of the embodiment described above, afastening portion is formed from the rivet hole (first through hole) 306of the first side wall portion 302 of the clutch drum 30, the rivet hole(second through hole) 402 a of the second side wall portion 402 of theclutch drum 40, and the rivet 53 that is inserted into the rivet hole306 and the rivet hole 402 a to hold together the first side wallportion 302 and the second side wall portion 402 a. The fasteningportion is provided between the first engagement side oil chamber (firstclutch oil chamber) 34 enclosed by the clutch drum (first clutch drum)30 and the clutch piston (first piston) 35, and the second engagementside oil chamber (second clutch oil chamber) 44 enclosed by the clutchdrum 30 and the clutch piston (second piston) 45. By thus using therivets 53 to hold together the first side wall portion 302 of the clutchdrum 30 and the second side wall portion 402 of the clutch drum 40 tofix the clutch drum 30 and the clutch drum 40, there is no need toprovide a snap ring and a section on a support member of the clutch drum40 (in the embodiment, the clutch drum 30) required for holding the snapring, and the fastening portion can be provided between the firstengagement side oil chamber 34 and the second engagement side oilchamber 44. Therefore, an increase in the axial length can be suppressedto achieve a more compact device. In addition, torque is transmittedbetween the clutch drum 30 and the clutch drum 40 through the rivets 53.There is thus no need to form a spline for transmitting torque betweenthe clutch drum 30 and the clutch drum 40, and processing costs can bereduced as a consequence. Note that the cross-sectional shapes of therivet holes 306, 402 a are not limited to circular shapes, and may berectangular grooves or the like.

The rivet holes 306 that respectively include the second and third holeportions 306 b, 306 c of the first side wall portion 302 of the clutchdrum 30 are each formed with an inner diameter that becomes smaller fromthe outer side toward the clutch drum 40 side of the clutch drum 30. Bythus forming each of the rivet holes 306 of the first side wall portion302 of the clutch drum 30 with an inner diameter that becomes smallerfrom the outer side toward the clutch drum 40 side of the clutch drum30, if the rivets 53 are caulked from the outer side of the clutch drum30, the rivets 53 can sufficiently fill the rivet holes 306 and therivets 53 can be more strongly fixed to the clutch drum. 30.

In addition, the clutch C1 includes the cancel plate 36, the clutch C2includes the cancel plate 46, and at least a portion of the clutch C2overlaps with the clutch C1 as viewed from the radial direction. Asshown in FIG. 1, the portion where the clutch drum 30 and the clutchdrum 40 (as well as the cancel plate 36) are fastened is included withinthe range of the axial width DO of the first engagement side oil chamber34 and the first cancel oil chamber 37 that are spaces (oil chambers)enclosed by the clutch drum 30 and the cancel plate 36, and the secondengagement side oil chamber 44 and the second cancel oil chamber 47 thatare spaces (oil chambers) enclosed by the clutch drum 30 and the cancelplate 46. Specifically, the portion where the clutch drum 30 and theclutch drum 40 (as well as the cancel plate 36) are fastened is includedwithin the range of the axial width Dl of the first engagement side oilchamber 34 and the first cancel oil chamber 37 that are the oil chambersof the clutch C1, and within the range of the axial width D2 of thesecond engagement side oil chamber 44 and the second cancel oil chamber47 that are the oil chambers of the clutch C2. Thus, an increase in theaxial length can be suppressed to achieve a more compact automatictransmission 20.

The second side wall portion 402 of the clutch drum 40 contacts thecancel plate 36, and the cancel plate 36 and the second side wallportion 402 of the clutch drum 40 are fastened to the clutch drum 30.Thus, deformation of the clutch drum 40 caused by a force from thecancel plate 36 due to the centrifugal hydraulic pressure generated inthe first cancel oil chamber 37 of the clutch C1 can be suppressed. Morespecifically, when the cancel plate 36 presses the clutch drum 40 due tothe centrifugal hydraulic pressure generated in the first cancel oilchamber 37, the fulcrum point (portion where the clutch drum 40 and theclutch drum 30 are fastened) and the force point (section where theclutch drum 40 supports the cancel plate 36, i.e., portion of contactbetween the inner circumferential portion 363 of the cancel plate 36 andthe second side wall portion 402 of the clutch drum 40) of a torsionalmoment that acts on the clutch drum 40 correspond to substantially thesame position. Therefore, a large torsional moment acting on the clutchdrum 40 can be suppressed, and deformation of the clutch drum 40 can bewell suppressed. Fixing the cancel plate 36 between both the clutch drum30 and the clutch drum 40 eliminates the need for providing a sealstructure for the cancel plate 36 to suppress the leakage of hydraulicoil from the first cancel oil chamber 37. However, as shown in FIG. 7,the cancel plate 36 may not be fastened to the fixing portion 304,provided that an end surface of the inner circumferential portion 363 onthe left side of the figure is supported by the clutch drum 40 in thevicinity of the coupled portions of the clutch drum 30 and the clutchdrum 40. By thus fastening the clutch drum 40 to the clutch drum 30 inthe vicinity of the section where the clutch drum 40 supports the cancelplate 36, when the cancel plate 36 presses the clutch drum 40 due to thecentrifugal hydraulic pressure generated in the first cancel oil chamber37 of the clutch C1, the fulcrum point and the force point of atorsional moment that acts on the clutch drum 40 approach each other.Therefore, a large torsional moment acting on the clutch drum 40 can besuppressed, and deformation of the clutch drum 40 can be suppressed.

The ring-shaped fixing portion 304 extends from the first side wallportion 302 of the clutch drum 30. The aligning portion 305 is formedaxially extending from the inner circumferential side of the fixingportion 304. The cancel plate 36 and the clutch drum 40 are fitted tothe aligning portion of the fixing portion 304 and fastened to thefixing portion 304. Thus, the clutch drum 30, the cancel plate 36, andthe clutch drum 40 can be easily fastened together. In addition, byfitting the cancel plate 36 and the clutch drum 40 to the aligningportion 305 axially extending from the fixing portion 304, the cancelplate 36 and the clutch drum 40 can be easily aligned.

Moreover, the clutch piston 35 of the clutch C1 can move in the axialdirection by hydraulic pressure supplied to the first engagement sideoil chamber 34 on the inner circumferential side of the clutch drum 30,and defines together with the first cancel plate 36 the first cancel oilchamber 37 for canceling centrifugal hydraulic pressure. The clutchpiston 45 of the clutch C2 can move in the axial direction by hydraulicpressure supplied to the second engagement side oil chamber 44 on theinner circumferential side of the clutch drum 40, and defines togetherwith the cancel plate 46 the second cancel oil chamber 47 for cancelingcentrifugal hydraulic pressure. The clutch drum 30 includes the innercylinder portion 303 that axially extends from the inner circumferentialportion of the first side wall portion 302. The clutch piston 35 issupported axially slidable by the fixing portion 304 of the clutch drum30, and defines the first engagement side oil chamber 34 together withthe first outer cylinder portion 301, the first side wall portion 302,and the fixing portion 304 of the clutch drum 30. The clutch piston 45is supported axially slidable by the inner cylinder portion 303 of theclutch drum 30 and formed so as to slidingly contact the innercircumferential surface of the fixing portion 304 of the clutch drum 30,and defines the second engagement side oil chamber 44 together with theinner cylinder portion 303, the first side wail portion 302, and thefixing portion 304 of the clutch drum 30. By thus utilizing the fixingportion extending from the first side wall portion 302 of the clutchdrum 30, the clutches C1 and C2 can be easily configured.

It should be noted that the present invention is not limited to theautomatic transmission 20 of the embodiment, and may obviously beapplied to a manual transmission as well.

Here, the correspondence between main elements of the embodiment andmain elements of the invention as described in the Summary of theInvention will be explained. In the embodiment, the clutch C1 includingthe clutch drum 30 and the clutch piston 35 corresponds to a “firstclutch”; the clutch C2 including at least the clutch drum 40 and theclutch piston 45, and disposed circumferentially inward of the clutch C1to a “second clutch”; the first engagement side oil chamber 34 enclosedby the clutch drum 30 and the clutch piston 35 to a “first clutch oilchamber”; the second engagement side oil chamber 44 enclosed by theclutch drum 30 and the clutch piston 45 to a “second clutch oilchamber”; the rivet hole 306 of the first side wall portion 302 of theclutch drum 30 to a “first through hole”; the rivet hole 402 a of thesecond side wall portion 402 of the clutch drum 40 to a “second throughhole”; and the rivet 53 that is inserted into the rivet hole 306 and therivet hole 402 a, and holds together the first and second side wallportions 302, 402 to a “rivet”.

Note that with regard to the correspondence between the main elements ofthe embodiment and the main elements of the invention as listed in theSummary of the Invention, the embodiment is only one specific examplefor carrying out the invention explained in the Summary of theInvention. This correspondence does not limit the elements of theinvention as described in the Summary of the Invention. In other words,any interpretation of the invention described in the Summary of theInvention shall be based on the description therein; the embodiment ismerely one specific example of the invention described in the Summary ofthe Invention.

The above embodiment was used to describe an example for carrying outthe present invention. However, the present invention is notparticularly limited to such an example, and may obviously be carriedout using various embodiments without departing from the scope of thepresent invention.

The present invention may be used in the manufacturing industry of atransmission device.

1-7. (canceled)
 8. A transmission device comprising: a first clutch thatincludes a first clutch drum and a first piston; and a second clutchthat includes a second clutch drum and a second piston, and is disposedcircumferentially inward of the first clutch, wherein the first clutchincludes a first clutch oil chamber enclosed by the first clutch drumand the first piston, the second clutch includes a second clutch oilchamber enclosed by the first clutch drum and the second piston, and afastening portion, formed from a first through hole of a first side wallportion of the first clutch drum, a second through hole of a second sidewall portion of the second clutch drum, and a rivet that is insertedinto the first and second through holes and holds together the first andsecond side wall portions, is provided between the first clutch oilchamber and the second clutch oil chamber.
 9. The transmission deviceaccording to claim 8, wherein the first through hole of the first clutchdrum is formed with an inner diameter that becomes smaller from an outerside toward a second clutch drum side of the first clutch drum.
 10. Thetransmission device according to claim 8, wherein the fastening portionis disposed circumferentially inward of the first clutch oil chamber andcircumferentially outward of the second clutch oil chamber.
 11. Thetransmission device according to claim 8, wherein the first clutchfurther includes a first cancel plate, the second clutch furtherincludes a second cancel plate, and at least a portion of the secondclutch overlaps with the first clutch as viewed from a radial direction,and at least a portion of the fastening portion is included within arange of a width, in an axial direction of the transmission device, of aspace enclosed by the first clutch drum and the first cancel plate and aspace enclosed by the first clutch drum and the second cancel plate. 12.The transmission device according to claim 11, wherein the second sidewall portion of the second clutch drum contacts the first cancel plate,and the first cancel plate and the second side wall portion of thesecond clutch drum are fastened to the first clutch drum.
 13. Thetransmission device according to claim 11, wherein a ring-shaped fixingportion axially extends from the first side wall portion of the firstclutch drum, and an aligning portion is formed axially extending fromthe fixing portion, and the first cancel plate and the second clutchdrum are fitted to the aligning portion of the fixing portion andfastened to the fixing portion.
 14. The transmission device according toclaim 13, wherein the first piston of the first clutch is axiallymovable by hydraulic pressure supplied to the first clutch oil chamberon an inner circumferential side of the first clutch drum, and definestogether with the first cancel plate a first cancel oil chamber thatcancels centrifugal hydraulic pressure, the second piston of the secondclutch is axially movable by hydraulic pressure supplied to the secondclutch oil chamber on an inner circumferential side of the second clutchdrum, and defines together with the second cancel plate a second canceloil chamber that cancels centrifugal hydraulic pressure, the firstclutch drum includes an inner cylinder portion that axially extends froman inner circumferential portion of the first side wall portion, thefirst piston is supported axially slidable by the fixing portion of thefirst clutch drum, and defines the first clutch oil chamber togetherwith the first side wall portion and the fixing portion of the firstclutch drum, the second clutch drum axially supports the first cancelplate, and the second piston is supported axially slidable by the innercylinder portion of the first clutch drum and formed so as to slidinglycontact an inner circumferential surface of the fixing portion of thefirst clutch drum, and defines the second clutch oil chamber togetherwith the inner cylinder portion, the first side wall portion, and thefixing portion of the first clutch drum.